Damped spring



Sept. 3, 1968 R. L. CARLSON Filed Feb. 25, 1966 4 Qu,7///////////////////// ///////VW |1T ,Q .www l N N ,E \\\\w\\\\\ Q QNI 1w QW, l h k 1 w A ,www NT. mw QW MVT' United States Patent O 3,399,380DAMPED SPRING Robert L. Carlson, Chicago, Ill., assignor to W. H. MinerInc., Chicago, Ill., a corporation of Delaware Filed Feb. 23, 1966, Ser.No. 529,585 4 Claims. (Cl. 267-1) ABSTRACT F THE DISCLOSURE A dampedspring having an elongated casing with a prim-ary chamber filled with acompressible solid eccentric to the longitudinal axis of the casing andreceiving a piston, and a communicating auxiliary chamber whereby anadditional volume of compressible solid is available whereby toaccommodate increased travel of the piston and its associated pistonrod.

My present invention relates generally to a damped spring and moreparticularly to a long travel damped spring.

In general, -a damped spring comprises casing means with a primarychamber therein, a piston rod extending outwardly of the primary chamberfor receiving impact forces, and a piston at the end of the piston rodwithin the primary chamber. The piston provides axial orifice means, andthe primary chamber is filled with a compressible solid. As the pistonrod moves into the primary chamber in response to impact forces, thereduction in volume of the compressible solid, and the throttling effectproduced by the compressible solid being forced through the orificemeans, impose a damping and spring force on the piston rod and piston.

It is an object of =my present invention to provide a dambed spring, ofthe general type described, wherein the primary chamber that receivesthe piston communicates with an auxiliary chamber whereby additionalvolume of compressible solid is afforded to accommodate long travel ofthe piston rod.

It is another object of my present invention to provide a damped spring,as described, wherein the casing means thereof is elongated and theprimary and auxiliary chambers are substantially coextensive in an axialdirection. This general arrangement of the cham-bers contributes tocompactness. p

It is a further object of my present invention to provide a dampedspring, as described, wherein the casing means comprises a cylinder thatdefines the primary chamber and a surrounding casing that defines withthe cylinder the auxiliary chamber. This specific constructionadditionally contributes to compactness.

-It is a still further object of my present invention to provide adamped spring, as described, wherein the primary and auxiliary chamberscommunicate through metering ports that serve to control the returnforce imposed on the piston rod as the compressible solid expands.

Now in order to acquaint those skilled in the art with the manner ofconstructing and using da-mped springs in accordance with the principlesof my present invention, I shall describe in connection with theaccompanying drawing, a preferred embodiment of my invention.

In the drawing:

FIGURE l is a longitudinal median sectional View of a damped springincorporating the principles of my present invention;

FIGURE 2 is a transverse sectional view, taken substantially along theline 2-2 in FIGURE 1, looking in the direction indicated by the arrows;and

FIGURE 3 is a view, partly in elevation and partly in section, takensubstantially along the line 3 3 in FIG- URE 1, looking in the directionindicated by the arrows.

3,399,880 Patented Sept. 3, 1968 ICC Referring now to the drawing, thereis indicated generally by the reference nume-ral 10 a damped spring-incorporating the principles of my present invention. The damped spring10 comprises an elongated casing 12 having a rear closed end wall 14, aforward end wall 16, and a forward cylindrical opening 18. The casing 12is generally oblong in cross-section, and the axis of the opening 18 iseccentric to the principal longitudinal axis of the casing 12.

Disposed axially within the casing 12 is a cylinder 20. The forward endof the cylinder 20 is seated in the opening 18, While the rear end ofthe cylinder 20 is seated in a counterbore 22 formed in the rear casingwall 14 and abuts a plate 24. The casing 12 and cylinder 20 togetherservel as casing means. The cylinder 20 defines interiorly a primarychamber 26, and the casing 12 defines with the cylinder 20 an auxiliarychamber 28. The primary and auxiliary chambers are maintained incommunication by a plurality of circumferentially spaced radial ports 30that are formed in the cylinder 20 adjacent the rear casing wall 14.

Mounted in the casing opening 18 is guide and seal means indicatedgenerally by the reference numeral 32. The guide and seal means 32 iscomprised of an annular piston rod bearing or gland 34 having an innerend 36 of reduced diameter that is received in the forward end of thecylinder 20. The gland 34 carries an O-ring or seal 38 that engages theperiphery of the casing opening 18, and also carries an annular packingor seal assembly 40. The gland 34 is maintained in proper axial positionagainst the forward end of the cylinder 20 by means of four ringsegments 42 engaged in an annular groove 44 formed in the casing walldefining the opening 18.

Extending through the gland 34 and the packing assembly 40, andprojecting into the primary chamber 26, is a piston rod 46. The outerend of the piston rod 46 is adapted to receive impact forces, while theinner end of the piston rod has secured thereon a piston 48. Theperiphery of the piston 48 is spaced from the interior cylindricalsurface of the chamber 26 to define axial orifice means in the form ofan annular orifice. Additionally, the primary and auxiliary chambers 26and 28 are filled with a compres-sible solid or elastomer 50 such assilicone rubber.

The rear casing wall 14 is formed with a charging port 52 having aconical valvel seat 54 that is engageable 4by a ball valve 56. The plate24, which serves to retain the ball valve 54 within the confines of theinner end of the charging port 52, is provided with apertures 58 throughwhich the charging port 52 communicates with the prima-ry chamber 26.The described ball check valve arrangement serves to permit theadmission of compressible solid into the chambers 26 and 28, and yetprevents I the escape of compressible solid therefrom, for example,between the time that charging means (not shown) is removed from theouter end of the port 52 and a filler plug 60 is inserted therein. Asshown in FIGURE 2, the casing 12 is provided with opposed lateralflanges 62 which are adapted to be secured by bolts 64 to a supportingframe 66.

In the operation of the damped spring 10, buff forces imposed on thepiston rod 46 cause the latter and the piston 48 to move inwardly of theprimary chamber 26 from the position shown in solid lines in FGURE ltoward the position shown in dotted lines. During such move ment, thevolume of the primary chamber 26V is reduced to the extent ofdisplacement by the piston rod, thus increasing the pressure of thecompressible solid 50 in both chambers 26 and 28. Concurrently, thecompressible solid 50 is forced through the annular orifice surroundingthe piston 48 thereby producing a throttling effect. The describedvolume-pressure change of the compressible solid,

and the attendant throttling effect, impose a damping and spring forceon the piston and the piston rod, and thereby serve to dissipate theenergy of the buff forces imposed on the piston rod 46.

The compressible solid 50 is initially precompressed or preloadedapproximately 3% and the corresponding internal pressure is about 5,000p.s.i. When the piston rod 46 reaches the innermost end of travel shownin dotted lines, the compressible solid is compressed an -additional8-l2% and the corresponding internal pressure is then about 35,000p.s.i. Because of the provision of the auxiliary chamber 28 whichaffords additional volume of compressible solid, the reduction in volumeof the compressible solid `caused by piston rod displacement is limitedas indicated, and long travel of the piston rod is accommodated.Furthermore, because the primary and aux. iliary chambers 26 and 28 arearranged substantially coextensive in an axial direction and are definedby the casing 12 and cylinder 20 in the manner described, long travel ofthe piston rod is attained in a compact construction.

When the buff forces are removed from the piston rod 46, or areotherwise fully dissipated, the pressure of the compressible solid 50,acting on the unbalanced area of the piston rod 46, Causes the piston 48and piston rod 46 to return to the solid-line position shown inFIGURE 1. During the return stroke of the piston rod 46, thecompressible solid flows back through the annul-ar orifice surroundingthe piston 48 to fill the space being vacated by the latter.Correspondingly, the pressure f the compressible solid 50 returns to thenormal preload pressure. In this connection, the preload pressure servesto assure positive return of the piston rod and piston to the normalrest position shown in solid lines. Finally, the ports 30, which may bevaried in size, serve to meter compressible solid therethrough andthereby control the return force imposed on the piston rod as thecompressible solid expands.

While I have shown and described what I believe to be a preferredembodiment of my present invention, it will be understood by thoseskilled in the art that various rearrangements and modifications may bemade therein without departing from the spirit and scope of myinvention.

I claim:

1. A damped spring comprising a horizontally disposed generallyelongated casing which is generally oblong in a vertical direction, oneend of said casing being closed by a rear wall and the opposite endbeing provided with a partial end wall defining a circular opening inthe upper portion of the casing, a cylinder and piston unit mounted inthe upper portion of said casing with a piston rod projecting outwardlyof said opening and adapted to receive impact blows, the inner end ofsaid cylinder being ported to provide communication between a primarychamber defined within said cylinder and an auxiliary chamber defined bythe inner surface of said casing and the outer surface of said cylinder,axially extending orifice means in the piston of said cylinder andpiston unit, and a compressible solid filling both said primary andauxiliary chambers whereby compression of said compressible solid uponinward movement of said piston and piston rod provides both a dampingand reutrn force on said piston, said axially coextensive auxiliarychamber providing a greater volume of said solid to be compressedwhereby to permit a greater inward travel of said piston and rod for agiven length casing and cylinder.

2. The damped spring of claim 1 wherein the inner end of said cylinderis seated in a recess provided on the inner surface of said casing rearWall and the outer end of said cylinder is seated in said circularopening defined by said partial end wall, and wherein annular guide andseal means is disposed in said circular opening defined by said partialend wall and in the adjacent end of said cylinder for guiding andsealing said piston rod.

3. The damped spring of claim 2 wherein said ported inner end of saidcylinder comprises a series of circumferentially spaced radial portswhereby to provide communication between said primary and auxiliarychambers.

4. The damped spring of claim 1 wherein said axially extending orificemeans in said piston comprises an annular orifice defined between theperiphery of said piston and the inner surface of said cylinder, andwherein a ball-check-valve controlled charging port for filling saidchambers with said compressible solid is provided in said casing endwall.

References Cited UNITED STATES PATENTS 2,778,627 l/1957 Sands 267-13,053,526 9/1962 Kendall 267-64 3,152,798 10/1964 Jarret et al. 267-13,294,391 12/1966 Smith et al 267-64 3,306,598 2/1967 Jarret et al267-64 FOREIGN PATENTS 299,872 8/ 1965 Netherlands.

ARTHUR L. LA POINT, Primary Examiner. R. M. woHLFARTH, AssisfamExaminer.

